catalog1 := {
    "x-1": "a-phone",
    "x-2": "b-phone",
    "y-1": "a-pad"
}

catalog2 := {
    "104": "a-watch",
    "105": "b-watch",
    "108": "a-phone"
}

have_common_item if {       # catalog1 and catalog2 have some item in common
    some value1 in catalog1
    some value2 in catalog2
    value1 == value2
}

catalog := {
    "x-1": {"name": "a-phone", "suppliers": ["a-corp", "z-corp"]},
    "x-2": {"name": "b-phone", "suppliers": ["b-corp", "z-corp"]},
    "y-1": {"name": "a-pad", "suppliers": ["a-corp"]}
}

has_supplier_b_corp if {       # some product has some supplier "b-corp"
    some item in catalog
    some supplier in item.suppliers
    supplier == "b-corp"
}
